docs: def _get_child_class(self, path):
          """ Return the appropriate child class given a subdirectory path.
          
          Args:
              path (str): The path to the subdirectory.
          
          Returns: An uninstantiated BIDSNode or one of its subclasses.
          """
          if self._child_entity is None:
              return BIDSNode
  
          for i, child_ent in enumerate(listify(self._child_entity)):
              template = self.available_entities[child_ent].directory
              if template is None:
                  return BIDSNode
              template = self.root_path + template
              # Construct regex search pattern from target directory template
              to_rep = re.findall(r'\{(.*?)\}', template)
              for ent in to_rep:
                  patt = self.available_entities[ent].pattern
                  template = template.replace('{%s}' % ent, patt)
              template += r'[^\%s]*$' % os.path.sep
              if re.match(template, path):
                  return listify(self._child_class)[i]
  
          return BIDSNode